The present invention pertains to a device for adapting combined brake and turn signal lights on a trailer to the independent brake and turn signal lights on a towing vehicle. There are two systems for actuating the turn signal and brake signal lamps in use in most vehicles in this country, often resulting in incompatability between the towing vehicle and the towed vehicle. One system, most commonly found on foreign-made cars, provides separate and independent lamps, or lamp filaments, for brake and directional turn indicators. The other, used on all American-made cars and some late-model foreign cars, combines these two functions into a single lamp for brake signal and turn signal indicators. In the latter case, there are separate left- and right-hand lamps, both of which light up for brake signals, while the left-hand lamp flashes for left turn signal and the right-hand lamp for right turn signal. The electrical system of the vehicle provides means for inactivating the brake signal of the lamp on that side for which the turn signal is operating, so that when the right-hand turn signal is flashing, only the left-hand lamp is lighted by the brake signal, and vice versa. When this latter system is employed in a towing vehicle, and the former system on a trailer, the interface connections are limited to directional signal only or brake signal only, as the towing vehicle does not provide any means for inactivating the brake signal when the directional indicator is being operated.
Heretofore, the only legal solution to the problem has been to install an additional set of lights on the trailer to match those of the towing vehicle. This is a tedious and time-consuming process, which not only detracts from the aesthetic appearance of the trailer, but also makes the wiring incompatible with that of a towing vehicle having the combined turn signal and brake signal system.